Fiber Optic Cabling 101

I thought I’d create a quick and dirty little cheat sheet for dealing with fiber optic cabling and the different connector types we usually have to deal with.  For the most part, when dealing with fiber cables there are really 3 things you need to know:

–          Length needed

–          Connector types

–          Cable type/size

Now if you don’t know how to determine what length you need – well then you probably should click HERE to link to a site that won’t strain your brain quite so much or run to your local hardware store for a quick lesson on how to use a tape measure.  The rest of you please read on.

There are lots of connector options for fiber cables but I’ll concentrate on the ones we run into most often – LC – SC and ST.  When specing out cabling these connectors are usually designated as a combination such as LC/LC or LC/SC each designating which type of connector is on each end.  Here is what these connectors look like:

ST

 

 

 

 

 

SC

 

 

 

 

 

LC

 

 

 

 

 

ST cables were one of the first widely used fiber cable connections.  ST stands for “Straight Tip” and while it was widely used for many years it has been slowly replaces by smaller and more dense connections. These connectors have a twist on/off type connector.

SC connectors are similar to the ST type connections but use a push-on/pull-off type connector which is easier to use that the ST type cable connector.

LC connectors are probably the more reconizable and current type of connector.  These were developed by Lucent Technologies – hence the “LC” designation.  These connectors work similar to an RJ45/RJ11 plug and simply clip in.

The type of connectors you use will obviously be determined by the equipment you are trying connect together and the type of SFP’s at each end.  For example if we are connecting a Fiber Channel EMC Clariion SAN to a Cisco MDS switch we usually use LC/LC cables with LC connectors on both ends.

So now we know what how long of a cable we need and what connections we need so we should be good to go right?  Well, yes and no.  There is one other detail we need to take into consideration and that is cable width.  Generally speaking there are 2 options – 62.5 micron and 50 micron which will usually be designated 50/125 micron and 62.5/125 micron.

In the past, fiber core diameter were extremely important details in fiber optic transmission but improvements in fiber technology have reduced that importance.  Newer 850nm lasers offer increased transmission rates and smaller spot size requirements in the fiber’s core. These new lasers and the low cost and high-bandwidth capacity of 50-micron fiber allow both gigabit and 10-gigabit data transfer rates at an affordable price point.  62.5-micron fiber is also capable of gigabit and 10-gigabit data transfer rates but 50-micron fiber offers better reliability and increased distances.  50-micron fiber has three times or more the bandwidth capacity of 62.5-micron fiber and this enables it to achieve longer distances when new lasers are used.

Deciding between 62.5-micron and 50-micron fiber may seem like a given but it will depend on whether you are installing a new network  an upgrading/replacing an existing network.  62.5 and 50 micro cables can be joined but there are plenty of gotchas to watch out for so you’ll want to consult a networking professional to avoid data loss and connection issues.

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